Computer mail systems, also known as electronic mail systems, allow a first user to send messages by electronic transmission to a second user. In general, the user to whom a message is sent is referred to as the addressee or recipient of the message and the user that sends the message is referred to as the sender.
Several computer mail systems have been developed to allow electronic transmission of electronic mail between users. Each computer mail system has a distinct electronic mail format, which includes protocols for addressing, formatting and sending electronic mail. Generally, electronic mail formatted for use on one computer mail system can not be used on a second mail system unless the format is converted to the format of the second mail system.
An organization, such as a company or a division within a company, generally uses the same computer mail system throughout the organization. In this case, all electronic mail sent within the organization can be easily transmitted from the sender to the recipient, because both the sender and the recipient are using the same computer mail system and the electronic mail need not be converted from one format to a different format. However, if a user within an organization desires to send electronic mail to a user at another organization, then that electronic mail must be converted from the electronic mail format of the sender organization, namely the sender's format, to the electronic mail format of the recipient organization, namely the recipient's format, if the sender's format differs from the recipient's format.
Two different computer mail systems having different electronic mail formats may be connected by means of a gateway. A gateway is a device used to connect networks or computer mail systems using different communication protocols and formats. A gateway both transfers information and converts the information to a format compatible with the format and protocols of the recipient organization's computer mail system.
However, many practical problems arise when a sender desires to send electronic mail to a recipient using a different computer mail system. For example, the sender at the sender organization does not always know the electronic mail format used by the computer mail system at the recipient organization to which the electronic mail is being sent. In this case, some prior art devices will send the message in the sender's format relying on the recipient to have a gateway which can convert the electronic mail from the sender's format into the recipient's format. One disadvantage of these prior art systems is that, as the different types of electronic mail systems proliferate, there is an ever increasing likelihood that the recipient organization will not have a gateway or conversion program which can convert electronic messages from the sender's format into the recipient's format. Also, while many gateways can convert electronic mail to different formats, several gateways cannot cleanly convert the attachments to electronic mail, such as drawings.
A further disadvantage is that the cost of acquiring gateways that can convert electronic messages from a number of different formats to the recipient's format increases greatly as additional types of electronic mail systems are introduced and gain prominence. This disadvantage is compounded by the fact that various existing types of electronic mail formats are occasionally revised, thereby necessitating gateways which can convert different versions of the same electronic mail format.
Another way the prior art systems attempt to overcome the disadvantage of not knowing the recipient's format is to convert all of the sender's electronic mail to a common or standard format, such as the American Standard Code for Information Interchange (ASCII), or, the Extended Binary Code Decimal Interchange Code (EBCDIC). However, this approach suffers from the disadvantage that by converting electronic mail to these types of standard systems, any word processing encoding, such as paragraph indent, carriage return and underlining, is often stripped from the electronic mail. In addition, if the electronic mail comprises an attachment, such as a drawing, the attachment is often garbled. In addition, many electronic mail formats inherently encrypt the message to increase security during transmission, but this encryption and added security is lost when the electronic mail is converted into a standard format, leaving the standard formatted electronic mail accessible to others.
Another way in which the prior art systems have attempted to overcome these disadvantages is by keeping a directory of the various recipients to whom users at a sender organization may desire to send electronic mail. The disadvantage of this approach is that the directories are complex structures and they are dependent on the users at specific recipient organizations rather than dependent on the recipient organization itself. In this way, a large number of information regarding individual recipients must be kept at directories located at the sender organizations. In addition, these directories must be updated to reflect changes and locations of recipients and changes in the electronic mail systems used by the recipient organizations. Any change of information regarding a potential recipient, such as a change in the recipient's location, a change in their employment or a change in the recipient's format used by the recipient organization, must be reflected in the directory.
The administrative process of ensuring that all directories are current and correct is called "directory synchronization". Directory synchronization is a complex task, and becomes increasingly complex as the number of potential recipients in the directories increases. While there are some tools to help with directory synchronization, the task of ensuring that changes in the directories are complete and efficient is one of the most daunting tasks now facing electronic mail delivery systems. In some cases, directory synchronization can be a barrier to building a workable computer mail system.